The present invention relates to a plough guide for underground mining ploughs, with angle plates, whose extended arm is fastened on the working face side to a conveyor pan of a chain scraper conveyor and whose base arm towards the face, supported on the ground, forms a sliding track for the plough, with upper and lower chain channel slides for the plough chains separated by distance pieces fastened preferably at a distance from each other on extended arms of the angle plates, with a cover closing the chain channels to the working face side and which can be pivoted towards the face, having at least one abutment part, which can be fixed on the plough guide and released, and with a guide rail arranged on the plough guide at a distance from the sliding plough track.
Plough guides are known to comprise individual guide troughs which, on the working face side, are built onto the conveyor pans of the chain scraper conveyor forming the line of pans and in mining operation form a positive guide for the plough body moving along the working face. The drive to the plough body is effected by means of a circulating plough chain guided in chain channels in the plough guide, whereby the traction strand is formed as a rule by the lower chain channel, in which an arm or similar of the plough body can engage from outside. Owing to the plough chain being moved along the whole face all the plough guides are subject to heavy vibration independently of the instantaneous position of the plough. The plough guides are subject to extraordinarily high demands, especially high deforming forces, a high rate of wear and the vibrations previously mentioned. Extreme loading always arises when the plough body passes through the individual plough guides and its whole weight is supported on the upper guide formed from the guide rail, on the lower guide formed by the lower chain channel and the guide beam and on the slide track.
Previously proposed plough guides are known in different forms of construction, for instance from DE 37 37 525 A1. In this previously proposed plough guide the guide rail forming the upper guide is welded onto the head of a cover formed by a covering cap and a foot region of the cover forms the pivot bearing. In the closed position of the cover a foot section of the guide rail lies on welding pieces, which are welded onto the extended arm of the angle plate. Since the cover cap must be able to bear the weight of the mining plough, the foot section of the guide rail is fastened by a screwed connection to the extended arm of the angle plate or the welded pieces welded onto it. The screwed connection comprises strong centring screws for this, which sit in matching clearance holes in the foot section, with large surface centring pieces. Collar nuts are screwed onto the threaded shafts of the centring screws, with which the abutment faces on the mating surfaces formed from the extended arms of the angle plate are maintained relatively large. By the matching of the close toleranced clearance holes engaged through by the centring screws on the one hand a precise height centring of the guide rail and at the same time a large surface support for it can be achieved, so that a reliable acceptance of the high vertical forces acting on the guide rail as the plough passes over is provided.
In spite of the centring screws used in the previously proposed plough guide, having threaded shafts of reduced diameter and large area collar nuts, the screwed connections securing the closed position of the cover cap can become loose, which can be traced back to the high vibrations and vertical forces, which in the operation of the plough body and the plough traction chain are exerted on the foot region of the covers formed as a pivoting joint.
It is an aim of the present invention therefore to produce plough guide slides, in which these disadvantages are avoided, wherein especially the loosening of the screwed connection securing the closed position is counteracted, so that overall a reliable formation of the plough guide slide is achieved.
Accordingly the present invention is directed to a plough guide as described in the opening paragraph of the present specification, in which the abutment part of the cover is clamped in between the angle plate and a securing part at a distance from the cover screwed to the angle plate.
Owing to the movement according to the invention of the fastening axis of the screwed connection out of the region of the cover cap and the abutment parts the formerly present rigid screw connection between the cover cap and the plough guide is replaced by a clamp fixing loaded only indirectly by the forces acting on the cover. Even unfavourable horizontal or bending forces acting on the foot area of the cover during the sliding along of the plough do not affect the screw fastening of the securing part, since the cover cap guided in principle loosely in the head region can perform equalising movements.
Preferably the securing part has a clamping arm engaging over the abutment part. Advantageously the securing part is configured with two arms and has a strong cross arm provided with through holes for fastening screws, which preferably is fastened to the plough guide above the cover by means of the fastening screws, whereby the clamping arm directed towards the ground engages over the abutment part. With this configuration the securing part can be reliably fixed by means of screw fastenings tightened with high torque to the plough guide, whilst the clamping arm prevents the opening of the cover by a positive engagement. At the same time with this arrangement for avoidance of high levered forces a favourable separation between the fastening axis of the screw fastening of the securing part and the resultant forces transmitted by the abutment part acting on the clamping arm can be obtained.
In order to counteract the vibrations introduced in the plough guide, in a preferred embodiment one or more damping element(s) is/are arranged between the abutment part and the arm of the angle plate and/or between the abutment part and the securing part. Advantageously the damping element comprises a preferably elastic or plastic deformable bolt(s) or similar which can be inserted in a through hole in the abutment part, whose length is preferably greater than the depth of the abutment part, so that the region of the damping element extended above the abutment part is deformed during the assembly and fastening of the securing part and acts to damp the vibrations between the abutting adjacent metal surfaces. An expedient deformation can especially be achieved if the bolt is formed with a collar or head section, whose outer diameter is greater than the internal diameter of the through hole. Alternatively the damping element comprises plates, knobs, or rails of elastic or plastic deformable material, attached to the abutting surfaces of the abutment part, of the clamping arm of the securing part or the extended arm, especially screwed on, fitted into or glued on, which again damp the vibrations between the individual metal surfaces lying on each other. Both the named embodiments with a damping element are advantageous, if due to the dimensions of the cross arm in the assembled condition a gap, filled out by the deformed damping element, preferably with a gap width of some 1 to 2 mm is formed between the clamping arm and the abutment part and/or between the abutment part and the extended arm. The elastic or plastic damping element can spread out under compression, so as to prevent or damp vibrations.
In a further advantageous embodiment of the invention the guide rail forming the upper guide for the plough is combined with the extended arm of the angle plate or is a component of this arm and the abutment part of the cover and the securing part are clamped or screwed onto a foot section of the guide rail or to the extended arm. By this embodiment the guiding forces exerted on the upper guide can be supported immediately via the angle plate so thatxe2x80x94in contrast to the previously known embodimentxe2x80x94the cover is not exposed to the high plough forces. The foot section of the guide rail or with integral conformation of the guide rail and the angle plate their horizontal arm hereby offers a sufficient designed anchoring cross section for the screwed connection of the securing parts.
Advantageously the abutment part comprises abutment rails formed on the head of the cover or welded on, whereby the cover is secured to the extended arm by means of several, especially by means of two securing parts. Preferably the cover is formed from a cover cap, which can be mounted to fold at its lower, ground facing end in hinge joints, which are preferably mounted at the height of the slide distance pieces. In a preferred embodiment the hinge joints only require here to accept the force of the weight of the cover cap enclosing the upper chain channel.
Advantageously the abutment part with the exception of the clamping lies essentially loosely on the arm of the angle plate.